The present invention relates to a cutting tool having a cutting insert retained in an insert receiving pocket by means of a clamping pin. More particularly, the clamping pin is actuated by means of a clamping screw engaged in a side face of the cutting tool.
Cutting tools having a cutting insert retained in an insert receiving pocket by means of a clamping pin are known. Such a tool is shown, for example, in U.S. Pat. No. 4,615,650 to Hunt. As shown in FIGS. 4 and 5 of xe2x80x98650, a cutting insert 6 is retained in a recess 4 of a tool holder 2. The cutting insert 6 is secured by passing a locking pin 8 through a cutting insert bore 10. The locking pin 8 includes a first portion 28 dimensioned for insertion through the cutting insert bore 10 and a second adjacent portion 30 dimensioned for insertion into a first bore 22 of the tool holder. Engagement means include a pocket 58xe2x80x2 which extends into the second portion 30 at an angle relative to the axis 56xe2x80x2 and is defined by a wall 60xe2x80x2 which is preferably cup-shaped. A drawing member 24xe2x80x2 is in the form of a set pin having preferably a rounded end to bear against the cup-shaped wall 60xe2x80x2.
When tightening the set pin it is urged against the wall 60xe2x80x2 thereby pushing the locking pin 8 further into the first bore 22 so that the locking pressure is exerted in a first direction 36 downwardly on the front portion of the cutting insert bore 10, and, in a second direction 44 rearwardly on the rear portion of the cutting insert bore 10.
In the tool of xe2x80x98650, the set pin 24xe2x80x2 is directed rearwardly with respect to the tool and is generally in the same plane as the locking pin 8. Such an arrangement is not suitable when it is required to operate the clamping screw from a side face of the tool, that is, perpendicular to the view in FIG. 5 of xe2x80x98650.
Another tool of the above kind is shown in Japanese Publication Number 11291105 A to Masayuki. As shown in xe2x80x98105, a crank pin 25 having a head 26 is inserted in both a body insertion hole 23 in a tool body 11 and an insertion hole 22 in a tip 15 mounted on a tip attachment seat 13. An oblong hole 23a extends to an intersection of two side walls 13b, 13c of the tip attachment seat 13 so that it regulates a slanting direction of the crank pin 25 in the body insertion hole 23. By pressing a cylindrical shaft 27 of the crank pin 25 by a fixed screw 30, the crank pin 25 is pulled in so that it slants and the tip 15 is pressed and fixed to a bottom face 13a of the tip attachment seat 13 and the side walls 13b, 13c by means of the head 26.
In the tool of xe2x80x98105, since the crank pin 25 passes through the tip 15 into the insertion hole 23, it is necessary to dismantle the crank pin in order to replace the tip 15. Also, in such an arrangement, the fixed screw 30 is generally directed in, or slanted with respect to, the direction of the plane in which the crank pin 25 moves. The fixed screw 30 cannot be perpendicular to the movement direction of the crank pin 25 and be separated therefrom if it is required to operate the fixed screw from such a direction.
Another tool of the above kind is shown in U.S. Pat. No. 3,491,421 to Holloway. As shown in FIG. 8 of xe2x80x98421, a tool holder 10C is provided with a bore 65 enlarged at 66 for providing a shoulder 67 between the two bores. A wobble pin 20C has a lower tapering portion 70 having an inwardly arched groove 71 adjacent its lower end. A flange 72 is provided between the tapered shank portion 70 and an upwardly extending bulging end 24C. The flange 72 is arched on its edge at 73 so as to be rockably mounted in the enlarged portion 66. The wobble pin 20C is held in place by a silicone rubber 74 that enters into the groove 71.
The wobble pin 20C is actuated by a push rod 59 having a front rounded end 61 and a rear bevel surface 60. A screw 63, having a tapered end 62, pushes the push rod 59 onto the wobble pin 20C, thereby pushing forwardly the lower tapering portion 70. The tilting motion of the pin 20C, enabled by the shoulder 67 that holds the flange 72, moves rearwardly the bulging end 24C thereby retaining rearwardly the cutting insert 30 against the side walls of its pocket.
A disadvantage of the tool of xe2x80x98421 is that the pin 20C has to be held by a silicone rubber 74 so that it will not move upwardly by the pushing of the push rod 59. Furthermore, the production of the tool with a bore with two portions of different diameters complicates the tool and increases its cost.
Another tool of the above kind is shown in British Patent No. 1 341 651. As shown in xe2x80x98651, a radially symmetrical clamping lever 3 forces a cutting plate 1 rearwardly against an upstanding shoulder 10 of a pocket in a shank 9. The lever 3, disposed in a cylindrical bore, comprises two conically tapered arms 4 and 6 so that its fulcrum 8 is intermediate its ends. A collar 5 is provided at the outer end of the lever arm 3. The second lever arm 6 is provided in its outer end portion with a groove 7. Since the clamping lever 3 is radially symmetrical, the groove 7 extends all around the clamping lever 3. A clamping screw 14 extends parallel to the cylindrical bore at the shank. A wedge-shaped intermediate member 17, having a cylindrical peripheral surface and an oblique wedge surface 18, is pushed by the intermediate member 20. A forward end 19 of the intermediate member 17, that pushes forwardly the lever arm 6, is ridged and extends into the groove 7 of the lever arm 6 so that the clamping lever 3 cannot fall out even when the clamping screw 14 is loose.
According to the construction of the clamping lever 3, the forwardly pushing of the forward end 19 of the intermediate member 17 against the groove 7 causes a lever action around the fulcrum 8 thus urging rearwardly the cutting plate 1 by means of the collar 5. A disadvantage of the tool of xe2x80x98651 is that the cutting plate 1 is urged only rearwardly and it cannot be urged downwardly against the bottom of the pocket in the shank 9.
It is an object of the present invention to provide a cutting tool that significantly reduces or overcomes the aforementioned disadvantages.
In accordance with the present invention there is provided a cutting tool comprising a holder and a cutting insert, having a first through bore, mounted in an insert receiving pocket of the holder, the insert receiving pocket has a base wall and at least one side wall, a second bore of the holder extends downwardly from the base wall, a third bore of the holder extends rearwardly from the second bore and opens into a fourth bore of the holder, the fourth bore is slanted at a first slant angle (xcex1) with respect to the third bore;
a locking pin inserted in the second bore protrudes upwardly into the first through bore, the locking pin has an upper portion and a lower portion having a front side and a rear side, a protrusion extends rearwardly from the upper portion, the lower portion has a rearwardly facing groove that is substantially co-aligned with the third bore, a forward end of the groove is substantially closer to the front side of the lower portion than to the rear side of the lower portion;
a plunger received in the third bore, a forward portion of the plunger protrudes forwardly into the second bore and is in contact engagement with a forward portion of the groove, a rear portion of the plunger protrudes rearwardly into the fourth bore and has a first engagement surface transversely directed to a first axis (A) of the plunger;
a clamping member engaged in the fourth bore, the clamping member has a second engagement surface in contact engagement with the first engagement surface;
in a first position of the cutting tool, the protrusion of the locking pin is spaced forwardly from a retaining portion at a rear portion of the first through bore of the cutting insert;
in a second position of the cutting tool, the second engagement surface of the clamping member applies pressure to the first engagement surface of the plunger thereby urging forwardly the forward portion of the plunger against the forward portion of the groove of the locking pin, a first contact point in an upper section of the lower portion of the locking pin is pressed to a forward portion of the second bore and the protrusion of the locking pin presses downwardly and rearwardly the retaining portion at the rear portion of the first through bore of the cutting insert thereby securely retaining the cutting insert in the insert retaining pocket against the base wall and the at least one side wall of the insert receiving pocket.
Typically, the second bore of the holder is perpendicular to the base wall.
Generally, the second bore is substantially aligned with the first through bore.
Typically, the third bore is perpendicular to the second bore.
Further typically, the third bore is parallel to the base wall.
Preferably, the first slant angle (xcex1) is obtuse.
Typically, the fourth bore is perpendicular to the second bore.
Further typically, the fourth bore is parallel to the base wall.
According to a specific embodiment of the present invention, the fourth bore is threaded.
Generally, the upper portion of the locking pin is generally cylindrical.
Further generally, the lower portion of the locking pin generally has a downwardly tapering frusto-conical shape.
Preferably, the forward portion of the groove in the lower portion of the locking pin has a front spherical surface that merges with a forwardly tapering frusto-conical surface rearward thereto.
Further preferably, the forward portion of the plunger has a spherical surface mating with the spherical surface of the groove.
Typically, a forward end of the spherical surface of the forward portion of the plunger is flat.
According to a specific embodiment of the present invention, the first engagement surface of the rear portion of the plunger is directed substantially at a second slant angle (xcex2) of 55xc2x0 with respect to the first axis (A) of the plunger in a top view of the plunger.
Advantageously, the second engagement surface of the clamping member directly presses the first engagement surface of the plunger.
Preferably, the clamping member constitutes a clamping screw.
Typically, a fourth distance (D4) between the forward end of the groove and an imaginary continuation of the rear side of the lower portion of the locking pin, taken in a plane perpendicular to a longitudinal axis (B) of the locking pin, is 4 to 5 times larger than a fifth distance (D5) between the forward end of the groove and the front side of the lower portion of the locking pin, taken in the same plane.
Generally, in the first position of the cutting tool the cutting insert is freely disengageable from the insert receiving pocket in an upward direction.
Preferably, a resilient member urges rearwardly the lower portion of the locking pin.
Further preferably, the resilient member is engaged within a fifth bore of the holder, the fifth bore partially opens into the second bore substantially perpendicular thereto.
Typically, the resilient member is made of rubber or silicon.